Circuit breaker



May 25, 1954 A. R. CELLERINI CIRCUIT BREAKER Filed Nov. 25, 1951 Fig.|.

` INVENTOR Albert R.C

WITNESSES: .4

ellerini. K BY W ATTORNEY Patented May 25, 1954 UNITED STATES BTENT OFFICE 2,679,564 CIRCUIT BREAKER Albert R. Ceilerini, Beaver inghouse Electric Corp Pa., assignor to Westoration, East Pittsburgh,

Pa., a corporation of Pennsylvania Application November 23, 1951,

Serial N0. 257,812

Claims. (Cl. `200-116) This invention relates to circuit breakers and more particularly to circuit breakers for controlling lighting and moderate power circuits.

sponsive element also in ambient temperatures.

Another object of the invention is to provide invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, to-

gether with additional objects and advantages ""i' thereof, will be best understood from the following detailed description of several modincations thereof when read in conjunction with the accompanying drawing.

In said drawing:

Figure 1 is a side elevational View, partly in section, of a circuit breaker embodying the principles of the invention;

Fig. 2 is an enlarged fragmentary elevational view of the trip device.

Fig. 3 is an enlarged fragmentary view showing a modification of the trip device.

Referring to Fig. 1 of the drawing, the circuit breaker comprises generally7 a base i i and a cover I3, both of molded insulating material, a stationary contact I5, a movable contact I?, an operating mechanism 99 and a trip device 2l. The stationary contact I5 is mounted on the inner end of a strip 23 of conducting material, to the `other end of which is secured a terminal connector 25.

The movable contact end of a spring Contact l1 is carried on the free arm 27 which is secured switch member 29. The electrically connected by Vmeans of `a flexible conductor 3l to the current responsive trip means of the trip device 2l which will hereinafter be described. The current responsive trip means is, in turn, connected to a conducting strip 33 connected at its outer end to a terminal connector 35.

The movable switch member 29 is pivotally mounted on a pin 37 supported in the side walls of a generally U-shaped frame 39 secured to the base Il of the breaker housing. A stop pin t! supported between the sides oi the frame 39 cooperates with projections d3 on the U-shaped switch member 229 to limit the opening movement of the switch member.

The operating mechanism I 9 is mounted in the frame 39 and comprises a U-shaped operating lever t5 having 1ts legs pivoted on pivot members l? struck out from the frame 39, a releasable 39, a pair of toggle links and 5l and overcenter springs 59 (only one being shown). The toggle links 55 and 51 are pivotally connected together by means of a knee pivot pin 6|. The inner toggle link 55 is pivotally connected by means of a pin vc3 to U-shaped switch member 29 and the toggle link 457 is pivotally connected at its outer end by means of a pin to the releasable The overcenter springs 5S have their outer ends connected to the bight portion of the U-shaped operating lever 45, and their inner ends are connected to the knee pivot pin Si of the toggle 55-51. An operating handle 'El of molded insulating material is secured to the outer end of the operating lever 45 and is provided with a handle portion which extends through an opening 59 in the cover I3. The operating handle is also provided with an arcuate portion 'il which serves to substantially close the opening t3 in all positions of the handle. Lugs 73 struck out from the sides of the frame 39 serve as stops to limit the opening and closing movement of the operating lever 45.

The breaker contacts are opened manually by clockwise movement of the operating handle from the position in which it is causes collapse of the toggle 55-5L thereby moving the movable contact to the open position with a snap action. The contacts are closed by actuate the toggle 55-51 to its extended overset positions shown, thereby moving the movable contact to the closed position with a snap action.

The trip device 2! comprises a bimetal element 15 having a mounting foot 11 rigidly secured by means of a screw 'I9 to the base il or the housing. A main portion 8| of the bimetal element 15 extends at right angles to the mounting foot 11 and the outer or free end thereof is looped as at 83 so that a portion 85 of the bimetal element extends back substantially parallel to the main body 8| but spaced therefrom. The portion 85 of the bimetal element has secured thereto a latch member 01 which engages a latch 89 secured to but insulated from the carrier lever 49 to releasably restrain the carrier lever in the postion shown. A flexible conductor 9| connects the bimetal element 15 at the point approximately midway between the mounting foot 11 and the end of the portion 85 to the conducting strip 93.

The high expansion side of the main body 8| of the bimetal element is on the left (Fig. l), on the inside of the loop 83 and on the right of the portion 85. Only that portion of the main body 8l of the bimetal element between mounting member and the point of connection of the flexible conductor 9| is traversed by the current of the circuit. The loop 83 and the portion 95 of the bimetal element are responsive to the temperature of the surrounding medium. An increase in the temperature of the surrounding medium, which would cause the main body of the bimetal element to bend toward the right, would cause the loop 83 to tend to straighten out and the portion 85 to bend toward the left, thus maintaining a substantially constant latch overlap. If the temperature of the surrounding medium decreases, the main body 8| of the bimetal will bend toward the left, whereas`the loop 03 will tend to close and the portion S of the bimetal element will bend toward the right maintaining the proper overlap of the latch elements 8 -89.

The lower portion of the bimetal element below the flexible conductor 9| is heated in response to the iiow of overload currents therethrough, and, when heated a predetermined amount, bends toward the right moving the loop 83 and the portion 85 therewith to disengage the latch member 81 from the latch 89 to release the carrier lever 49. Upon release of the carrier lever 49, the

force of the overcenter springs 59 rotates the .y

carrier counterclockwise ing the pivot 65 across to the left of the overcenter springs 59, whereupon the springs cause collapse of the toggle 55--51 and opening of the contacts.

Before the breaker can be closed following an automatic opening operation, it is necessary to reset and relatch the carrier lever 49. This is accomplished by movement of handle and the operating lever to the full clockwise position. During this movement, a projection 99 on the operating lever 45 engages a shoulder on the carrier lever 49 and rotates the carrier lever in a clockwise direction. Near the end of the clockwise movement of the carrier lever, the latch 89 wipes by the latch member B1 slightly bending the bimetal element which thereafter resumes its latching position. The contacts are then closed in the previously described manner by counterclockwise movement of the operating lever.

According to the modification illustrated in Fig. 3, a bimetal element 94 is rigidly mounted by means of a screw 95 to the base of the housing. The free end of the bimetal element is looped as at 91 so that a portion 99 thereof extends back substantially parallel to the main body |0| of the bimetal element. The portion 99 of the bimetal element has secured thereto a latch member |03 which engages the latch 89 about its pivot 5|, movon the carrier lever 49 and releasably restrains the carrier lever 49 (Fig. l). The bimetal element 94 is connected to the conducting strip 33 by a flexible conductor |05 and a flexible conductor |01 connects the end of the portion 99 of the bimetal element to the movable contact |1.

The high expansion side of the bimetal element 94 is on the right of the main body |0| thereof, on the outside of the looped portion 91 and on the left of the portion 99. That portion of the bimetal element between the points of connection of the flexible conductors |05 and |01 is heated in response to the current ilow therethrough. That portion of the bimetal element 93 below the point of connection of the flexible conductor |05 is responsive to the temperature of the surrounding medium. A rise in the temperature of the surrounding medium would cause the main body |01 of the bimetal element to bend toward the left, would cause the loop portion 91 to contract and the portion 99 to bend toward the right, thus maintaining a substantially constant latch overlap. If the temperature of the surrounding medium decreases, the portions of the bimetal will bend in the opposite directions and maintain the proper overlap of the latch elements |03--09.

The portion of the bimetal element between the points of connection of the flexible conductors |05 and |01 is heated in response to the flow of overload currents therethrough, and when heated a predetermined amount the loop portion 91 contracts and the portion 99 bends toward the right to disengage the latch member |03 from the latch 99 and release the carrier lever 49 (Fig. 1). This effects automatic opening of the breaker in the previously described manner.

The invention provides a circuit breaker having a novel thermally responsive trip device comprising a thermal trip means formed from a single strip of bimetallic material, one portion of which comprises the tripping element and another portion serves to compensate the tripping portion of the thermal element for changes in ambient temperatures.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes and modifications may be made in the structural details thereof without departing from the spirit of the invention.

I claim as my invention:

l. ln a circuit breaker comprising relatively movable contact means and releasable operating means therefor, a trip device comprising a single bimetal element having one end supported and the other end free, said bimetal element having a reverse bend about a transverse axis parallel to its faces to form a loop, said bimetal element having the high expansion side on the inside of said loop, means electrically connecting only a portion of one leg of said bimetal element to be traversed by current of the circuit, latch means on the other leg of said bimetal element releasably restraining said operating means, the legs of said bimetal element moving in opposite directions in response to changes in ambient temperature to compensate said trip device foi changes in ambient temperature, and therma bending of said bimetal element in response t( overload currents causing said latch means t1 release said operating means and automatic open ing of said contact means.

2. In a circuit breaker comprising relativel movable contact means and operating means re l-leasable to effect legs of unequal length, said bimetal element vbein the circuit of the breaker so that only a portion of the longer leg is heated by the current of the circuit, the high and low expansion sides of said bimetal element being so arranged that the legs of said bimetal element move relative to each other in response to changes of ambient temperature to compensate said trip device, .and thermal bending of said bimetal element in response to overload currents operating means and opening of said contact means.

3. A circuit breaker comprising separable contact means and operating means releasable to cause separation of said contact means, a trip .device for eilecting release of said operating means comprising a single bimetal element having a return bend about a transverse axis parallel to its faces metal element being on the inside of said loop, support means supporting the longer leg of said bimetal element, latch means on the shorter leg of said bimetal element cooperating with said operating means to releasably restrain said operof said longer leg is traversed by the current of the circuit to be heated thereby, the current traversed portion of said bimetal element when axis parallel to its faces to form a loop, said bihigh expansion side means connecting a element in the circuit of the breaker to be heated by the current of the circuit, means securing one leg of said biinside of said loop, means supporting one leg of said bimetal element, means at the other leg of said bimetal element for eiecting release of said means connecting a portion only of said bimetal in the circuit of the breaker to be heated by the current in the circuit, said heated portion vof said bimetal element when heated by overload currents deilecting and moving said loop to eiect release of said releasable G. In a circuit abley con automatic opening of said contact means, a trip device comprising a single U-shaped bimetal element normally restraining said operating means, -said bimetal element having legs of unequal length, said bimetal element being electrically connected in the circuit of the breaker' so that only a portion thereof is heated by the current of the circuit, the high and lov,7 expansion sides of said bimetal element being so arrangedv that the legs of said bimetal element move relative to each other in response to changes in ambient temperature to compensate said trip device, and thermal bending of said bimetal element'vvhen heated in response to overload currents causing said bimetal element to release said operating means.

7. A circuit breaker having means releasable to cause automatic opening of said breaker, a

having a reverse bend about a transverse axis parallel to its faces to form a loop, means connecting a portion only of said bimetal element in the circuit of the response to changes in ambient temperature to compensate said trip device.

8. In a circuit breaker having relatively movable contact means means, a trip device comprising a single U-shaped bimetal element normally restraining said operating means, said bimetal element having legs of unto a iixed member, means at the other leg of said bimetal element for initiating release of said operating means, and the legs of said bimetal compensate said trip bient temperature.

9. A circuit breaker having means releasable to cause automatic opening of said breaker, a trip device comprising a bimetal element formed a reverse bend about a transverse axis parallel to its faces to form a loop, said bimetal element side on the outside of said loop, means supporting one leg of said bimetal element, latch means operable by the other leg of circuit of the breaker to be heated by the current of the circuit, said heated portion of said bimetal element when heated by overload currents deflecting and causing said latch means to release said releasable means, and the legs of said bimetal element moving relative to each other in response to changes in ambient temperature to compensate said trip device.

10. A circuit breaker having separable contactl means and operating means releasable to cause separation of said contact means, a trip device for eiecting release of said operating means comprising a single bimetal element having a reverse bend about a transverse axis parallel to its faces to form a loop having legs of unequal length, the high expansion side of said bimetal element being on the outside of said loop, support means supporting the longer leg oi said bimetal element, latch means operable by the shorter leg of said bimetal element cooperating with said operating means to releasably restrain said operating means, means electrically connecting said bimetal element in the circuit of the breaker so that a portion of the longer leg, said loop and said shorter leg are traversed by the current of References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,216,748 Lindemann Oct. 8, 1940 2,318,279 Aschvvanden May 4, 1943 2,370,206 Taylor Feb. 2'7, 1945 2,378,648 Maseng June 19, 1945 2,459,629 Dorfman et al. Jan. 18, 1949 

